In the 21st century, when most people live so far removed from food production, it's easy to forget that food can only be grown on a small fraction of our planet. Good farmland is a rare and precious resource worldwide, and North America is blessed with an abundance of it. Indeed, a wealth of productive farmland is one reason the United States grew and prospered so quickly.
Yet America's most valuable resource is also the most endangered. In the US, cities sprang up in regions where land was the richest. But as those cities continue to expand, they threaten a tremendous amount of America's best farm and ranch land. Today, 86 percent of our produce comes from land directly in the path of urban and suburban growth.
A farm is not a factory or a gas station; it cannot simply be plunked down anywhere and produce the same results. You cannot grow Georgia peaches in Kansas, for instance, and some varieties of cherries can only be grown in Michigan.
Because of unplanned, ill-considered growth, an expanse of farmland the size of Delaware is lost to asphalt and buildings every year. Too much land is chopped into "ranchettes" - "too small to grow and too big to mow." Once the land is gone, it can't be brought back, and the ripple effect is tremendous.
When farmers are pushed off the most fertile soil, they are forced to rely more heavily on fertilizers, pesticides, and irrigation to do what the best land does naturally. Farms and ranches provide homes for more than 70 percent of the nation's wildlife. When we develop that land, we put America's biological diversity at risk.
With less local farming, the US is becoming more dependent on imported food - some from countries with less stringent environmental and safety regulations than our nation's standards.
Sprawl impacts our wallets, too. Growing neighborhoods costs taxpayers more to provide basic public services, such as schools and fire and police protection.
But it doesn't have to be this way. Communities across America are adapting innovative programs such as purchase of development rights to restrict new construction permanently. Areas like Lancaster, Pa.; Montgomery County, Md.; and Marin and Sonoma counties in California, are actively developing a vision for the future that includes agriculture.
Many farmers across the nation would like the same opportunity. When cities grow sensibly and farms and ranches thrive, Americans enjoy the benefits of urban vitality, healthy farms, and open space. But to get there, we need policies that encourage farmers to save the land that sustains us.
• Ralph Grossi is a rancher and president of American Farmland Trust.